Implement an mmap-based LM parser.
This commit is contained in:
Lukhnos Liu
parent
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commit
67775e3ccf
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//
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// FastLM.h: A fast unigram language model for Gramambular
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//
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// Copyright (c) 2012 Lukhnos Liu (http://lukhnos.org)
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//
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// Permission is hereby granted, free of charge, to any person
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// obtaining a copy of this software and associated documentation
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// files (the "Software"), to deal in the Software without
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// restriction, including without limitation the rights to use,
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// copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the
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// Software is furnished to do so, subject to the following
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// conditions:
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//
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// The above copyright notice and this permission notice shall be
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// included in all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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// OTHER DEALINGS IN THE SOFTWARE.
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//
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#include "FastLM.h"
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <fstream>
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using namespace Formosa::Gramambular;
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FastLM::FastLM()
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: fd(-1)
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, data(0)
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, length(0)
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{
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}
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FastLM::~FastLM()
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{
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if (data) {
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close();
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}
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}
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bool FastLM::open(const char *path)
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{
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if (data) {
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return false;
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}
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fd = ::open(path, O_RDONLY);
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if (fd == -1) {
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return false;
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}
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struct stat sb;
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if (fstat(fd, &sb) == -1) {
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return false;
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}
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length = (size_t)sb.st_size;
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data = mmap(NULL, length, PROT_WRITE, MAP_PRIVATE, fd, 0);
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if (!data) {
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::close(fd);
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return false;
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}
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// we have 5 states
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// 0
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// end -> end
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// lf -> forward, go to 0
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// space -> error
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// other -> record ptr, forward, goto 1
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// 1
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// end -> error
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// lf -> error
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// space -> zero out, check length, record ptr, go to 2
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// other -> forward, go to 1
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// 2
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// lf -> error
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// end -> error
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// space -> zero out, check length, record ptr, go to 3
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// other -> forward, go to 2
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// 3
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// end -> error
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// lf -> save row, zero out, go to 0
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// space -> error
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// other -> forward, go to 3
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char *head = (char *)data;
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char *end = (char *)data + length;
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char c;
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Row row;
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state0:
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if (head == end) {
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goto end;
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}
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c = *head;
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if (c == '\n') {
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head++;
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goto state0;
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}
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else if (c == ' ') {
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goto error;
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}
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row.value = head;
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head++;
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// fall through state 1
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state1:
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if (head == end) {
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goto error;
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}
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c = *head;
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if (c == '\n') {
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goto error;
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}
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else if (c == ' ') {
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if (row.value == head) {
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goto error;
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}
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*head = 0;
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head++;
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row.key = head;
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goto state2;
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}
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head++;
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goto state1;
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state2:
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if (head == end) {
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goto error;
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}
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c = *head;
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if (c == '\n') {
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goto error;
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}
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else if (c == ' ') {
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if (row.key == head) {
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goto error;
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}
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*head = 0;
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head++;
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row.logProbability = head;
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goto state3;
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}
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head++;
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goto state2;
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state3:
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if (head == end) {
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goto error;
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}
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c = *head;
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if (c == '\n') {
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if (row.logProbability == head) {
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goto error;
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}
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*head = 0;
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head++;
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keyRowMap[row.key].push_back(row);
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goto state0;
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}
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if (c == ' ') {
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goto error;
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}
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head++;
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goto state3;
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error:
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close();
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return false;
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end:
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static const char *space = " ";
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static const char *zero = "0.0";
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Row emptyRow;
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emptyRow.key = space;
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emptyRow.value = space;
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emptyRow.logProbability = zero;
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keyRowMap[space].push_back(emptyRow);
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return true;
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}
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void FastLM::close()
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{
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if (data) {
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munmap(data, length);
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::close(fd);
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data = 0;
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}
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keyRowMap.clear();
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}
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void FastLM::dump()
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{
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size_t rows = 0;
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for (map<const char *, vector<Row> >::const_iterator i = keyRowMap.begin(), e = keyRowMap.end(); i != e; ++i) {
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const vector<Row>& r = (*i).second;
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for (vector<Row>::const_iterator ri = r.begin(), re = r.end(); ri != re; ++ri) {
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const Row& row = *ri;
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cerr << row.key << " " << row.value << " " << row.logProbability << "\n";
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rows++;
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}
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}
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}
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const vector<Bigram> FastLM::bigramsForKeys(const string& preceedingKey, const string& key)
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{
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return vector<Bigram>();
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}
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const vector<Unigram> FastLM::unigramsForKeys(const string& key)
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{
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vector<Unigram> v;
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map<const char *, vector<Row> >::const_iterator i = keyRowMap.find(key.c_str());
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if (i != keyRowMap.end()) {
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for (vector<Row>::const_iterator ri = (*i).second.begin(), re = (*i).second.end(); ri != re; ++ri) {
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Unigram g;
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const Row& r = *ri;
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g.keyValue.key = r.key;
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g.keyValue.value = r.value;
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g.score = atof(r.logProbability);
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v.push_back(g);
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}
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}
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return v;
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}
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bool FastLM::hasUnigramsForKey(const string& key)
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{
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return keyRowMap.find(key.c_str()) != keyRowMap.end();
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}
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@ -0,0 +1,80 @@
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//
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// FastLM.h: A fast unigram language model for Gramambular
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//
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// Copyright (c) 2012 Lukhnos Liu (http://lukhnos.org)
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//
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// Permission is hereby granted, free of charge, to any person
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// obtaining a copy of this software and associated documentation
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// files (the "Software"), to deal in the Software without
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// restriction, including without limitation the rights to use,
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// copy, modify, merge, publish, distribute, sublicense, and/or sell
|
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// copies of the Software, and to permit persons to whom the
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// Software is furnished to do so, subject to the following
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// conditions:
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//
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// The above copyright notice and this permission notice shall be
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// included in all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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// OTHER DEALINGS IN THE SOFTWARE.
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//
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#ifndef FASTLM_H
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#define FASTLM_H
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#include <string>
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#include <map>
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#include <iostream>
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#include "LanguageModel.h"
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// this class relies on the fact that we have a space-separated data
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// format, and we use mmap and zero-out the separators and line feeds
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// to avoid creating new string objects; the parser is a simple DFA
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namespace Formosa {
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namespace Gramambular {
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class FastLM : public LanguageModel
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{
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public:
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FastLM();
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~FastLM();
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bool open(const char *path);
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void close();
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void dump();
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virtual const vector<Bigram> bigramsForKeys(const string& preceedingKey, const string& key);
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virtual const vector<Unigram> unigramsForKeys(const string& key);
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virtual bool hasUnigramsForKey(const string& key);
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protected:
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struct CStringCmp
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{
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bool operator()(const char* s1, const char* s2) const
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{
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return strcmp(s1, s2) < 0;
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}
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};
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struct Row {
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const char *key;
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const char *value;
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const char *logProbability;
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};
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map<const char *, vector<Row>, CStringCmp> keyRowMap;
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int fd;
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void *data;
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size_t length;
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};
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}
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}
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#endif
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